PHYWE 06676-00 Operating Instructions

PHYWE Systeme GmbH & Co. KG
Robert-Bosch-Breite 10
D–37079 Göttingen
Telefon +49 (0) 551 604–0
Fax +49 (0) 551 604–107
E-mail info@phywe.de
Internet www.phywe.com
Operating
instructions
TABLE OF CONTENT
1 SAEFTY PRECAUTIONS
2 PURPOSE AND CHARACTERISTIC
3 FUNCTIONAL AND OPERATING ELEMENTS
4 TECHNICAL DATA
5 WASTE DISPOSAL
1 SAEFTY PRECAUTIONS
Caution

Carefully read these operating instructions completely
before operating this instrument. This is necessary to
avoid damage to it, as well as for user-safety.

Only use the instrument for the purpose for which it was
designed.

Protect the device from dust, moisture and vapours. Clean
the device with a slightly damp, lint-free cloth. Harsh
cleaning agents or solvents are unsuitable.

Do not open the unit.
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Radiometer, Crookes type
Fig. 1: Radiometer, Crookes type 06676-00
2 PURPOSE AND CHARACTERISTIC
The Crookes radiometer 06676-00 (Fig. 1) serves to detect
radiation in the infrared and visible regions of the spectrum.
The explanation of its mode of action can be taken as confir-
mation of basic concepts of gas kinetics.
The Crookes radiometer consists of a glass vessel containing
a fused-in winged cross with four mica plates, each black-
ened on one side (radiometer system) on a rotating shaft. All
blackened surfaces point in the same direction of rotation. As
the gas pressure inside the vessel is adjusted to about 10
mbar, the free path length of the gas molecules is of the or-
der of () = 1 cm.
3 FUNCTIONAL AND OPERATING ELEMENTS
We will first consider only the events occurring for a single
wing of the radiometer. On average, just as many gas mole-
cules impinge on its blackened surface as on its unblackened
surface. 1. When the winged cross is illuminated with day-
light, with a light-bulb, an Hg high pressure lamp or with a
heat radiator, e.g. 04036-93, the blackened surfaces of the
wings are warmed up more strongly than the unblackened
surfaces, because of their higher absorption. A temperature
drop within the wings, from the blackened to the unblackened
side, therefore results. Because of this, the gas molecules
which strike the blackened (warmer) surface will be reflected
with greater speed (energy) than the molecules which strike
the unblackened (colder) surface. As .action and reaction re
equal., the gas molecules exert a larger recoil effect on the
blackened surface than on the unblackened surface. The
sum of all the individual recoils generates the radiometer
force. The direction of this force coincides with the direction
of the temperature drop which is generated in the wings. The
force exerted force causes the winged cross to be kept in
continual rotation.
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